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| Meta Title | Fever – adults | Healthify |
| Meta Description | A fever is when your core temperature is raised above 38°C. It usually means your body is reacting to an infection, such as a cold or flu. Find out how to manage it and when to seek medical help. |
| Meta Canonical | null |
| Boilerpipe Text | Key points about fever
A fever is when your core temperature is raised above 38°C. It
usually means your body is reacting to an infection, such as a cold or flu.
Â
Normal body temperature for children and adults is a
bout
37
°
C (degrees Celsius). You have a
fever if your temperature is 38
°
C
or over.
Â
Usually, you will feel unwell and hot, and you m
ay sweat. Sometimes you will feel very cold and shivery even when your temperature is high.
You can use a thermometer to find out how high your temperature is.Â
This page provides general information about fever. If you have a child with a fever, see
fever in children.
Normally
,
your
body
temperature
is
about
37
°C
but this can vary from person to person and at
different times
of the day
.
When
your
core
temperature
rises
above
38
°C
it’s
described
as
a fever or
high
temperature
.
If
your
temperature
is
39
°C
or
over
it’s
considered
to
be
a
high
fever
. You can use a thermometer to see how high you temperature is.
Read more aboutÂ
thermometers and how to use them.
You
can
often
get
a
fever
when
you
have
a
cold
or
flu
virus
,
but
there
are
other
reasons
why
your
temperature
might
be
high
.
If
you
have
a
fever
you
u
sua
l
ly
feel
unwe
l
l
and
can
f
eel
hot
a
nd
sweat
y
or
c
old
and
clamm
y
.
Th
is
page
is
a
b
ou
t
feve
r
in
a
d
ul
t
s
.
Rea
d
more
about
feve
r
in
c
h
il
d
ren.
Video: Fever in adults
Note this video is not intended to provide information about fever in children.
(Healthify He Puna Waiora, NZ, 2025)
A fever usually lasts 3 to 5 days, and most people recover by managing their symptoms at home. However, there are times when you should see a healthcare provider urgently for fever (see
when to seek help
below).Â
Drink plenty of fluids,
especially water or rehydration fluid (little and often is best). You sweat more when you have a fever. Drink enough so your urine (pee) is light yellow and clear. Read more about
dehydration
.
Avoid alcohol
as it can make you more dehydrated.
Rest
while you recover.
Open a window
for ventilation but avoid draughts.
Wear
lightweight comfortable clothing
and use lighter bedding. Don't use hot water bottles or electric blankets.
Use a cool cloth
to wash your face, hands and neck.
Change bed linen and clothing
regularly, especially if they are wet from sweat.
Although most fevers will settle down in a few days and are not worrying, you sometimes need to seek medical advice.
Note:
Older adults may not get a fever even if they have a serious infection. If an older adult is not eating or drinking or is confused, seek medical advice even if they
don't
have a fever.
When to contact a healthcare provider or call Healthline 0800 611 116 for advice 
Â
If you have a fever and:Â
your urine is darker than usual
Â
it lasts for more than 3 days or you seem to be getting sicker
Â
you’re shivering or shaking uncontrollably, or have chattering teeth, and it doesn’t stop within an hour or so
Â
you have a bad headache that doesn’t get better after taking pain medicines
Â
you’re having trouble breathing
Â
you’re getting confused or you’re unusually drowsy
Â
you have recently travelled overseas.
Â
If you have a fever and you are:Â
being treated for immune deficiency
Â
on immune-suppressant drugs, such as regular steroids, methotrexate, azathioprine or cyclophosphamide
Â
taking medication that can affect your immune system
Â
having, or have recently completed, treatment for cancer, leukaemia or lymphoma
Â
a transplant recipient
Â
HIV positive.
Â
If you’re pregnant and have a fever, check with your midwife, doctor or nurse before you take any medicines. If your fever lasts for longer than a day, talk to your lead maternity carer (LMC).
Â
Call 111 and ask for an ambulance or go to the nearest hospital
If you have a fever and any of the following symptoms:Â
Hallucinations.
Vomiting.
A stiff neck (unable to put your chin on your chest or have pain when moving your neck forward).
A skin rash.
Problems breathing.
A rapid heart rate.
A seizure (fit), or experience signs of a seizure about to happen, such as regular twitching or jerking.
A viral infection such as a cold, flu, COVID-19 or another respiratory tract infection is the most common cause of a fever. A bacterial infection, such as tonsillitis or pneumonia, is a less common cause but can be more serious.
Â
When you have an infection your body's natural reaction is to raise your body temperature to help kill off the virus or bacteria causing the infection.Â
Â
Other causes of fever include:
vaccination
allergy
drug reaction
hyperthyroidism
heat stroke
some cancers
inflammatory diseases, such as
connective tissue diseases
,
inflammatory arthritis
,
inflammatory bowel disease
tissue damage, eg, from a crush injury or surgery
Medicine
Â
As a fever is your body’s way of fighting infection, medicine isn’t needed for mild fever. However, you can take
paracetamol
if you also have a headache or muscle aches or pains. If your fever is due to a bacterial infection, you may need antibiotics to kill the bacteria, but antibiotics won’t help with a fever caused by a viral infection.Â
Â
Apps reviewed by Healthify
You may find it useful to look at some
symptom checkers
.
What is a high fever in adults?
A temperature of 39°C or over is considered to be a high fever.Â
When to worry about a high fever in adults?
A high fever by itself may not be anything to worry about but if you have other problems such as ongoing shivering, a bad headache, dark coloured urine, trouble breathing or confusion contact a healthcare provider or call Healthline on 0800 611 116 for advice.Â
If you have a high fever and hallucinations, vomiting, a stiff neck, skin rash, breathing problems, increased heart rate or have had a seizure, call 111 or get somebody to take you to the nearest hospital. Read more about
when to get help
.Â
How to care for a high fever at home?
Drink plenty of fluid (but not alcohol) to stay hydrated, rest, keep cool by wearing fewer clothes and opening a window, use a cool cloth for your face and hands and change clothes and bed linen regularly as they may get damp.Â
Need help now?
Credits:
Healthify editorial team. Healthify is brought to you by Health Navigator Charitable Trust.
Reviewed by:
Dr Emma Dunning, Clinical Editor and Advisor
Last reviewed:
18 Feb 2025
Page last updated:
23 Oct 2025 |
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3. [F](https://healthify.nz/health-a-z/f)
# Fever in adults
## Also known as a high temperature
### Key points about fever
- A fever is when your core temperature is raised above 38°C. It usually means your body is reacting to an infection, such as a cold or flu.
- Normal body temperature for children and adults is about 37°C (degrees Celsius). You have a fever if your temperature is 38°C or over.
- Usually, you will feel unwell and hot, and you may sweat. Sometimes you will feel very cold and shivery even when your temperature is high.
- You can use a thermometer to find out how high your temperature is.
- This page provides general information about fever. If you have a child with a fever, see [fever in children.](https://healthify.nz/health-a-z/f/fever-children "Fever – children")

QR Code
Print
Open all
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#### What is a fever? ( + VIDEO)
Normally, your body temperature is about 37°C but this can vary from person to person and at different times of the day. When your core temperature rises above 38°C it’s described as a fever or high temperature. If your temperature is 39°C or over it’s considered to be a high fever. You can use a thermometer to see how high you temperature is. Read more about [thermometers and how to use them.](https://healthify.nz/health-a-z/t/thermometers-how-to-use-them "Thermometers – how to use them")
You can often get a fever when you have a cold or flu virus, but there are other reasons why your temperature might be high. If you have a fever you usually feel unwell and can feel hot and sweaty or cold and clammy.
This page is about fever in adults. Read more about [fever in children.](https://healthify.nz/health-a-z/f/fever-children)
#### Video: Fever in adults
Note this video is not intended to provide information about fever in children.
(Healthify He Puna Waiora, NZ, 2025)
#### Looking after yourself when you have a fever
A fever usually lasts 3 to 5 days, and most people recover by managing their symptoms at home. However, there are times when you should see a healthcare provider urgently for fever (see [when to seek help](https://healthify.nz/health-a-z/f/fever-adults#when-to-seek-help) below).
- **Drink plenty of fluids,** especially water or rehydration fluid (little and often is best). You sweat more when you have a fever. Drink enough so your urine (pee) is light yellow and clear. Read more about [dehydration](https://healthify.nz/health-a-z/d/dehydration-adults).
- **Avoid alcohol** as it can make you more dehydrated.
- **Rest** while you recover.
- **Open a window** for ventilation but avoid draughts.
- **Wear** **lightweight comfortable clothing** and use lighter bedding. Don't use hot water bottles or electric blankets.
- **Use a cool cloth** to wash your face, hands and neck.
- **Change bed linen and clothing** regularly, especially if they are wet from sweat.
#### When to seek help
Although most fevers will settle down in a few days and are not worrying, you sometimes need to seek medical advice.
**Note:** Older adults may not get a fever even if they have a serious infection. If an older adult is not eating or drinking or is confused, seek medical advice even if they **don't** have a fever.
#### When to contact a healthcare provider or call Healthline 0800 611 116 for advice
**If you have a fever and:**
- your urine is darker than usual
- it lasts for more than 3 days or you seem to be getting sicker
- you’re shivering or shaking uncontrollably, or have chattering teeth, and it doesn’t stop within an hour or so
- you have a bad headache that doesn’t get better after taking pain medicines
- you’re having trouble breathing
- you’re getting confused or you’re unusually drowsy
- you have recently travelled overseas.
**If you have a fever and you are:**
- being treated for immune deficiency
- on immune-suppressant drugs, such as regular steroids, methotrexate, azathioprine or cyclophosphamide
- taking medication that can affect your immune system
- having, or have recently completed, treatment for cancer, leukaemia or lymphoma
- a transplant recipient
- HIV positive.
If you’re pregnant and have a fever, check with your midwife, doctor or nurse before you take any medicines. If your fever lasts for longer than a day, talk to your lead maternity carer (LMC).
| |
|---|
| Call 111 and ask for an ambulance or go to the nearest hospital **If you have a fever and any of the following symptoms:** Hallucinations. Vomiting. A stiff neck (unable to put your chin on your chest or have pain when moving your neck forward). A skin rash. Problems breathing. A rapid heart rate. A seizure (fit), or experience signs of a seizure about to happen, such as regular twitching or jerking. |
#### What causes a fever and do I need medicine? (+ APPS)
A viral infection such as a cold, flu, COVID-19 or another respiratory tract infection is the most common cause of a fever. A bacterial infection, such as tonsillitis or pneumonia, is a less common cause but can be more serious.
When you have an infection your body's natural reaction is to raise your body temperature to help kill off the virus or bacteria causing the infection.
Other causes of fever include:
- vaccination
- allergy
- drug reaction
- [hyperthyroidism](https://healthify.nz/health-a-z/o/overactive-thyroid)
- [heat stroke](https://healthify.nz/health-a-z/h/heat-stroke-and-heat-exhaustion)
- some cancers
- inflammatory diseases, such as [connective tissue diseases](https://healthify.nz/health-a-z/l/lupus), [inflammatory arthritis](https://healthify.nz/health-a-z/i/inflammatory-arthritis), [inflammatory bowel disease](https://healthify.nz/health-a-z/i/inflammatory-bowel-disease)
- tissue damage, eg, from a crush injury or surgery
#### Medicine
As a fever is your body’s way of fighting infection, medicine isn’t needed for mild fever. However, you can take [paracetamol](https://healthify.nz/medicines-a-z/p/paracetamol) if you also have a headache or muscle aches or pains. If your fever is due to a bacterial infection, you may need antibiotics to kill the bacteria, but antibiotics won’t help with a fever caused by a viral infection.
#### Apps reviewed by Healthify
You may find it useful to look at some [symptom checkers](https://healthify.nz/apps/s/symptom-checkers).
#### Related topics on Healthify
[How to use a thermometer](https://healthify.nz/health-a-z/t/thermometers-how-to-use-them "How to use a thermometer")
[Flu](https://healthify.nz/health-a-z/i/influenza)
[Meningococcal disease](https://healthify.nz/health-a-z/m/meningococcal-disease "Meningococcal disease")
[Pneumonia](https://healthify.nz/health-a-z/p/pneumonia "Pneumonia")
[Earache](https://healthify.nz/health-a-z/e/earache "Earache")
[Tonsillitis \| Pokenga repe korokoro](https://healthify.nz/health-a-z/t/tonsillitis "Tonsillitis | Pokenga repe korokoro")
[Rheumatic fever](https://healthify.nz/health-a-z/r/rheumatic-fever-children)
[Fever in children](https://healthify.nz/health-a-z/f/fever-children)
#### More information
[Influenza(external link)](https://info.health.nz/conditions-treatments/infectious-diseases/flu-influenza/ "Open external link") Health New Zealand \| Te Whatu Ora
[Thermometers – how to use them(external link)](https://www.kidshealth.org.nz/thermometers-how-use-them "Thermometers - how to use them") KidsHealth, NZ
#### Brochures
[After your immunisation(external link)](https://cdn.accentuate.io/5313605763230/11408390422661/HE2505_After_your_immunisation_0-v1593392974771.pdf "After your immunisation") HealthEd, NZ, 2019
#### Apps
[Symptom checkers](https://healthify.nz/apps/s/symptom-checkers)
#### References
1. [Fever and night sweats(external link)](https://patient.info/doctor/fever-and-night-sweats-pro "Open external link") Patient Info, UK, 2024
2. [Fever(external link)](https://info.health.nz/conditions-treatments/immune-system/fever "Open external link") Health New Zealand \| Te Whatu Ora, NZ
3. [Cold season – managing without antibiotics(external link)](https://bpac.org.nz/2018/cold-season.aspx "Open external link") BPAC, NZ, 2018
4. [Danger signs during pregnancy(external link)](https://info.health.nz/pregnancy-children/during-pregnancy/common-issues/ "Open external link") Health New Zealand \| Te Whatu Ora
5. [Fever in adults(external link)](https://www.nhsinform.scot/illnesses-and-conditions/infections-and-poisoning/fever-in-adults "Open external link") NHS Inform, UK, 2020
6. [Fever in adults(external link)](https://www.msdmanuals.com/home/infections/biology-of-infectious-disease/fever-in-adults "Open external link") MSD Manual Consumer Version, US
#### Information for healthcare providers
[Fever and night sweats(external link)](https://patient.info/doctor/fever-and-night-sweats-pro "Open external link") Patient Info Professional, UK, 2024
[Cold season – managing without antibiotics(external link)](https://bpac.org.nz/2018/cold-season.aspx "Open external link") BPAC, NZ, 2018
#### FAQs about fever in adults
#### What is a high fever in adults?
A temperature of 39°C or over is considered to be a high fever.
#### When to worry about a high fever in adults?
A high fever by itself may not be anything to worry about but if you have other problems such as ongoing shivering, a bad headache, dark coloured urine, trouble breathing or confusion contact a healthcare provider or call Healthline on 0800 611 116 for advice.
If you have a high fever and hallucinations, vomiting, a stiff neck, skin rash, breathing problems, increased heart rate or have had a seizure, call 111 or get somebody to take you to the nearest hospital. Read more about [when to get help](https://healthify.nz/health-a-z/f/fever-adults#when-to-get-help).
#### How to care for a high fever at home?
Drink plenty of fluid (but not alcohol) to stay hydrated, rest, keep cool by wearing fewer clothes and opening a window, use a cool cloth for your face and hands and change clothes and bed linen regularly as they may get damp.

[After your immunisation](https://www.healthed.govt.nz/system/files/resource-files/HE2505_After%20your%20immunisation_0.pdf "After your immunisation")
HealthEd, NZ, 2017

[Thermometers – how to use them](https://www.kidshealth.org.nz/thermometers-how-use-them "Thermometers - how to use them")
KidsHealth, NZ, 2015
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Credits: Healthify editorial team. Healthify is brought to you by Health Navigator Charitable Trust.
Reviewed by: Dr Emma Dunning, Clinical Editor and Advisor
Last reviewed: 18 Feb 2025
Page last updated: 23 Oct 2025
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[](https://healthify.nz/health-a-z/f/fever-adults)
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| Readable Markdown | ### Key points about fever
- A fever is when your core temperature is raised above 38°C. It usually means your body is reacting to an infection, such as a cold or flu.
- Normal body temperature for children and adults is about 37°C (degrees Celsius). You have a fever if your temperature is 38°C or over.
- Usually, you will feel unwell and hot, and you may sweat. Sometimes you will feel very cold and shivery even when your temperature is high.
- You can use a thermometer to find out how high your temperature is.
- This page provides general information about fever. If you have a child with a fever, see [fever in children.](https://healthify.nz/health-a-z/f/fever-children "Fever – children")

Normally, your body temperature is about 37°C but this can vary from person to person and at different times of the day. When your core temperature rises above 38°C it’s described as a fever or high temperature. If your temperature is 39°C or over it’s considered to be a high fever. You can use a thermometer to see how high you temperature is. Read more about [thermometers and how to use them.](https://healthify.nz/health-a-z/t/thermometers-how-to-use-them "Thermometers – how to use them")
You can often get a fever when you have a cold or flu virus, but there are other reasons why your temperature might be high. If you have a fever you usually feel unwell and can feel hot and sweaty or cold and clammy.
This page is about fever in adults. Read more about [fever in children.](https://healthify.nz/health-a-z/f/fever-children)
#### Video: Fever in adults
Note this video is not intended to provide information about fever in children.
(Healthify He Puna Waiora, NZ, 2025)
A fever usually lasts 3 to 5 days, and most people recover by managing their symptoms at home. However, there are times when you should see a healthcare provider urgently for fever (see [when to seek help](https://healthify.nz/health-a-z/f/fever-adults#when-to-seek-help) below).
- **Drink plenty of fluids,** especially water or rehydration fluid (little and often is best). You sweat more when you have a fever. Drink enough so your urine (pee) is light yellow and clear. Read more about [dehydration](https://healthify.nz/health-a-z/d/dehydration-adults).
- **Avoid alcohol** as it can make you more dehydrated.
- **Rest** while you recover.
- **Open a window** for ventilation but avoid draughts.
- **Wear** **lightweight comfortable clothing** and use lighter bedding. Don't use hot water bottles or electric blankets.
- **Use a cool cloth** to wash your face, hands and neck.
- **Change bed linen and clothing** regularly, especially if they are wet from sweat.
Although most fevers will settle down in a few days and are not worrying, you sometimes need to seek medical advice.
**Note:** Older adults may not get a fever even if they have a serious infection. If an older adult is not eating or drinking or is confused, seek medical advice even if they **don't** have a fever.
#### When to contact a healthcare provider or call Healthline 0800 611 116 for advice
**If you have a fever and:**
- your urine is darker than usual
- it lasts for more than 3 days or you seem to be getting sicker
- you’re shivering or shaking uncontrollably, or have chattering teeth, and it doesn’t stop within an hour or so
- you have a bad headache that doesn’t get better after taking pain medicines
- you’re having trouble breathing
- you’re getting confused or you’re unusually drowsy
- you have recently travelled overseas.
**If you have a fever and you are:**
- being treated for immune deficiency
- on immune-suppressant drugs, such as regular steroids, methotrexate, azathioprine or cyclophosphamide
- taking medication that can affect your immune system
- having, or have recently completed, treatment for cancer, leukaemia or lymphoma
- a transplant recipient
- HIV positive.
If you’re pregnant and have a fever, check with your midwife, doctor or nurse before you take any medicines. If your fever lasts for longer than a day, talk to your lead maternity carer (LMC).
#### Call 111 and ask for an ambulance or go to the nearest hospital
**If you have a fever and any of the following symptoms:**
- Hallucinations.
- Vomiting.
- A stiff neck (unable to put your chin on your chest or have pain when moving your neck forward).
- A skin rash.
- Problems breathing.
- A rapid heart rate.
- A seizure (fit), or experience signs of a seizure about to happen, such as regular twitching or jerking.
A viral infection such as a cold, flu, COVID-19 or another respiratory tract infection is the most common cause of a fever. A bacterial infection, such as tonsillitis or pneumonia, is a less common cause but can be more serious.
When you have an infection your body's natural reaction is to raise your body temperature to help kill off the virus or bacteria causing the infection.
Other causes of fever include:
- vaccination
- allergy
- drug reaction
- [hyperthyroidism](https://healthify.nz/health-a-z/o/overactive-thyroid)
- [heat stroke](https://healthify.nz/health-a-z/h/heat-stroke-and-heat-exhaustion)
- some cancers
- inflammatory diseases, such as [connective tissue diseases](https://healthify.nz/health-a-z/l/lupus), [inflammatory arthritis](https://healthify.nz/health-a-z/i/inflammatory-arthritis), [inflammatory bowel disease](https://healthify.nz/health-a-z/i/inflammatory-bowel-disease)
- tissue damage, eg, from a crush injury or surgery
#### Medicine
As a fever is your body’s way of fighting infection, medicine isn’t needed for mild fever. However, you can take [paracetamol](https://healthify.nz/medicines-a-z/p/paracetamol) if you also have a headache or muscle aches or pains. If your fever is due to a bacterial infection, you may need antibiotics to kill the bacteria, but antibiotics won’t help with a fever caused by a viral infection.
#### Apps reviewed by Healthify
You may find it useful to look at some [symptom checkers](https://healthify.nz/apps/s/symptom-checkers).
#### What is a high fever in adults?
A temperature of 39°C or over is considered to be a high fever.
#### When to worry about a high fever in adults?
A high fever by itself may not be anything to worry about but if you have other problems such as ongoing shivering, a bad headache, dark coloured urine, trouble breathing or confusion contact a healthcare provider or call Healthline on 0800 611 116 for advice.
If you have a high fever and hallucinations, vomiting, a stiff neck, skin rash, breathing problems, increased heart rate or have had a seizure, call 111 or get somebody to take you to the nearest hospital. Read more about [when to get help](https://healthify.nz/health-a-z/f/fever-adults#when-to-get-help).
#### How to care for a high fever at home?
Drink plenty of fluid (but not alcohol) to stay hydrated, rest, keep cool by wearing fewer clothes and opening a window, use a cool cloth for your face and hands and change clothes and bed linen regularly as they may get damp.


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Credits: Healthify editorial team. Healthify is brought to you by Health Navigator Charitable Trust.
Reviewed by: Dr Emma Dunning, Clinical Editor and Advisor
Last reviewed: 18 Feb 2025
Page last updated: 23 Oct 2025 |
| Shard | 132 (laksa) |
| Root Hash | 10202082698416572132 |
| Unparsed URL | nz,healthify!/health-a-z/f/fever-adults s443 |